Pipeline embolization device implantation in large carotid cavernous aneurysm associated with situs inversus totalis

Abstract

Situs anomalies are a heterogenous class of inborn visceral and vascular abnormalities with a broad range of radiographic characteristics. Situs inversus totalis is characterized by mirror image location of the heart and viscera relative to situs solitus (normal position). Few aberrations involving the neuraxis, and rarely intracranial aneurysms, have been reported in association with situs inversus totalis. We describe the radiological findings and endovascular management of one of the first of its kind: the association of bilateral carotid cavernous aneurysms (one large and the other small-sized) with situs inversus totalis.

Background

Situs inversus with dextrocardia or situs inversus totalis has been estimated to occur once in about 6000–8000 live births.¹ It has been described with several clinical presentations and associations, and uncommonly along with cerebral aneurysms.^2,3 To the best of our knowledge, Pipeline embolization device (PED) implantation for an intracranial large aneurysm is yet to be reported in association with situs inversus totalis. This report illustrates that rare association as well as the technical difficulty during endovascular treatment.

Case presentation and investigations

This 60-year-old lady presented to the outpatient department with complaints of right facial dysesthesias. Clinical examination was unremarkable. Magnetic resonance imaging brain could not be done as she underwent a permanent pacemaker insertion 20 years earlier for sick sinus syndrome (Figure 1(a)). Computed tomography (CT) brain along with a CT angiogram of intracranial vessels revealed bilateral carotid cavernous aneurysms. There was a large aneurysm on the right side (18 mm × 13.4 mm) and two aneurysms on the left cavernous segment with a proximal fusiform aneurysm (9.6 mm × 7 mm) and a distal saccular aneurysm (1.5 mm × 2.3 mm) (Figure 1(e) and (f)). CT chest and abdomen depicted features of situs inversus totalis with the aortic arch on the right side of the trachea and esophagus (Figure 1(b) and (c)). Digital subtraction angiography of the cerebral vessels revealed the origin of supra-aortic vessels from the aorta in the following order: left brachiocephalic artery, right common carotid artery (CCA) and right subclavian artery (Figure 1(d)). There were bilateral cavernous carotid aneurysms and cross flow was seen on manual carotid compression. Flow diverter stent (FDS) implantation was planned for the large right cavernous aneurysm.

Figure 1.

(a) Chest X-ray showing dextrocardia and right-sided arch along with a permanent pacemaker device on the left side of the chest. (b and c) Computed tomography of chest and abdomen depicting a right-sided aortic arch. Spleen is located on the right with the liver on the left. (d) Digital subtraction angiography of the aortic arch demonstrating the supra-aortic vessels (left brachiocephalic and right common carotid artery (RCCA) are visualized). Also seen is the left brachiocephalic artery bifurcating into left common carotid artery (LCCA) and left subclavian artery (LSA) along with the left vertebral artery (LVA) arising from LSA (e and f). Three-dimensional rotational angiography illustrating the large carotid cavernous aneurysm of the right internal carotid artery (RICA) and the two aneurysms from the left cavernous segment of the left internal carotid artery (LICA). Proximal fusiform aneurysm (arrowhead) and a distal smaller saccular aneurysm (arrow).

Treatment

She was started on dual antiplatelets for two weeks prior to the procedure. Through a transfemoral access, the right CCA was engaged with a 4fr Simmons 2 catheter (Merit Medical, USA). A 0.035-in Jindo wire (Cordis Corp, USA) was passed into the right external carotid artery over which the 4fr Simmons 2 catheter was exchanged with a 5fr Envoy MP catheter (Cordis Corp, USA). Over an Amplatz superstiff wire (Boston Scientific, USA) the 5fr Envoy MP catheter was exchanged with a 6fr Axcel guide sheath (Medikit Co, Japan). With the Axcel guide sheath parked in the right CCA, a 5fr Navien guide catheter (Medtronic, USA) was advanced into the right petrous internal carotid artery. A Marksman 0.027-in microcatheter (Medtronic, USA) was negotiated over a 0.014-in Asahi Chikai wire (Asahi Intec, Japan) distal to the aneurysm. To provide better stability during PED deployment, the Navien guide catheter was then advanced distal to the aneurysm coaxially over the Marksman catheter (Figure 2(a)). Over this triaxial support of Axcel guide sheath and Navien and Marksman catheters, a single 4.5 mm × 35 mm PED (eV3/Covidien, Plymouth, USA) was delivered across the targeted segment spanning the aneurysm neck. FDS was compacted at the neck of the aneurysm. Following the FDS placement, the vessel wall apposition was performed with TransForm (Stryker, USA) balloon angioplasty (Figure 2(b)). A cone beam CT and three-dimensional reconstructive angiography confirmed a good stent congruency with the vessel wall (Figure 3(c) and (d)). Control angiograms demonstrated the reduction of the inflow to the aneurysmal sac (eclipse sign) and contrast stasis (Figure 3(a) and (b)). A 24-hour follow-up CT brain was unremarkable. She tolerated the procedure well and was discharged after an uneventful post-procedure hospital stay of 5 days. No additional neurological symptoms were observed at the 1-month follow-up visit and she has been scheduled for a 6-month follow-up angiography.

Figure 2.

(a) Right internal carotid artery roadmap image showing Navien guide catheter (black arrow) and Marksman microcatheter (black arrowhead) positioned distal to the large carotid cavernous aneurysm. (b) Fluoroscopic image displaying TransForm balloon angioplasty (white arrowhead) of Pipeline embolization device.

Figure 3.

(a) Unsubtracted image demonstrating Pipeline embolization device (PED) (white arrows) across the aneurysm. (b) Digital subtraction angiography image illustrating contrast stasis in the aneurysm after PED deployment. (c) Three-dimensional rotational angiography demonstrating good stent position across the cavernous segment along with stent compaction (double arrowhead) at aneurysm neck. (d) Cone beam computed tomography showing good stent apposition of vessel wall.

Discussion

The term situs solitus refers to a normal position of asymmetric body parts. Situs inversus is the mirror image of situs solitus. Situs inversus can be further subdivided into situs inversus totalis and situs inversus with levocardia. Situs inversus totalis has the cardiac apex, spleen, stomach, jejunum, descending colon and aorta as right-sided structures. The liver, gallbladder, ligament of Treitz, ileum, ascending colon and inferior vena cava are left-sided structures.⁴

The embryo is symmetric in its early development. At approximately 18 days’ gestation, paired cardiac tubes appear which lengthen and rotate to the right over the next 4 days. This is the first sign of asymmetry in the embryo. Subsequently the cardiac apex moves from the right side of the thorax to the left. Dextrocardia results when the heart fails to migrate to the left thorax. Situs inversus totalis occurs when the cardiac tubes rotate to the left and the placement of the heart and other internal organs present a mirror image of the normal arrangement.⁵

The current opinion is that organ rotation and migration are mediated by a cascade of signals. Secretion of a protein named “Sonic hedgehog” (Shh) influences the expression of transforming growth factors referred to as Nodal, LEFTA, LEFTB and PITX2 in the lateral plate mesoderm. When these proteins are secreted on the left side of the embryo, the heart loops to the right, resulting in situs solitus. If the Shh protein is secreted on the right side, the heart loops to the left, resulting in situs inversus.^3,5 Only a small percentage of human situs defects could be identified from animal models. Meanwhile, the pathogenesis of intracranial aneurysms yet remains nebulous, although the research is still ongoing.³

The association of cerebral aneurysm and congenital cardiovascular anomaly has been reported. The myocardial and cervicocephalic arteries and the aortic arch originate from the neural crest. Thus, a developmental error originating from the neural ridge tissue may cause both cardiac abnormalities and intracranial aneurysms.⁶

Cerebral aneurysms associated with situs inversus totalis have been scantily reported.^2,3 The association of dextrocardia with situs inversus totalis and bilateral carotid cavernous aneurysms is a distinct clinical entity and a much infrequent event. There have been no prior reports describing this rarity.

Meticulous attention should be paid during cerebral angiography in this rare association. Because of their anomalous origin, cannulation of the supra-aortic vessels would be challenging.

The PED is an effective treatment for intracranial giant aneurysms,⁷ but complex aortic arch configuration limits endovascular access to the intracranial vessels for intervention. Therefore, techniques for navigating complex aortic arches are especially relevant to flow diversion interventions for giant aneurysms.⁸ In patients with right aortic arches, specialized catheters such as the Simmons catheters may facilitate common carotid artery access through the transfemoral approach.

Conclusion

Situs inversus totalis associated with large carotid cavernous aneurysm being successfully treated with a PED is being reported for the first time in literature. Complex aortic arches in these individuals would require special attention during endovascular procedures.

Author contributions

SC: conceptualization, manuscript drafting and data collection; HO: manuscript editing and technique formulation; KY: manuscript drafting, data collection and technical assistance; KT: data collection and technical assistance.

Declaration of conflicting interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The authors received no financial support for the research, authorship and/or publication of this article.